We hear a lot of talk about decarbonising economies, but what about one day decarbonising the atmosphere? Fortunately, two new technologies are on the horizon that hold promise to make this possible. It should also be cost effective, if we assume it’s worth paying $1trillion to draw CO2 back down to 350ppm.

The technologies are:

  • An electrochemical process to split seawater into an acid and base stream. The CO2 bubbles off inside the process.
  • Molten Salt Reactors that safely burn nuclear waste, providing electricity cheaper than coal. Covered here.

A by-product can be carbon neutral, zero-sulphur petrochemicals, if the existing Fischer-Tropsch process is applied with hydrogen. (Petrochemicals will be needed for the foreseeable future for long-haul transportation, aviation, agricultural and industrial prime movers.)

Extracting CO2 from air is horrendously expensive (priced optimistically at $600/tonne), however CO2 is very soluble in seawater, where the concentration is about 140 times higher than in the atmosphere. As we know, an equilibrium exists between atmospheric and oceanic CO2. So CO2 would move out of the air into the oceans.

The US Navy have been developing the technology as part of a process for synthesising jet fuel at sea, and this could be deployed at scale on coastal facilities. While the CO2 extraction method is novel, it’s similar to some existing large scale processes, including desalination.

The report below, from an Australian chemical engineer uses the cheapest Chinese nuclear power to cost the terrestrial operation. This comes out at $0.79 per litre for synfuel and $37 /tCO2 carbon capture. Power from a molten salt reactor based on static fuel tubes, will be cheaper.

There will be lots of business for the petrochemical industry, so we can hope that funding for climate denial may reduce, and a carbon tax, rebated back to families may become politically possible, as has already happened in British Columbia, Canada.

This kind of carbon tax is what is needed to incentivise CO2 drawdown. Carbon border duties – based on the energy intensity of economies – would need to become negative for countries doing net draw down of CO2.

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  1. Roger Clifton

    Given that there is a need for widespread desalination, it follows that CO2 can be extracted and converted to converted to synthene on the same scale that we burn hydrocarbons. We can thus speak of recycling carbon.

    When critics ridicule the “net” in “Net zero emissions by 2100” from the Paris Agreement, saying that we can’t bury CO2, we can now reply, “maybe, but we can recycle it”.

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